Introduction

Welcome amigo!

I created this wiki just for documenting some of the stuff that I have learnt. I use it as a quick reference to save time and kind of avoid relearning things. This whole wiki is specifically made for myself - so not everything in here is explained in detail and some of the pages may even contain mistakes.

Of course, if you have any questions or spot any mistakes, you are always free to contact me

What's on my Phone

Just some of the apps that I use my phone. I am not including every single one just the apps that I find useful.

Btw, I am an Android user and I use the OnePlus 7 as my daily driver.

  1. Raindrop

    In short, Raindrop is a cross-platform bookmanager with synchronisation so that I can access my bookmarks anywhere. I discovered Raindrop after watching MKBHD's What's on my Phone video and I really wanted to try it out. After using it for a couple of days, I thought to myself, how did I not use a bookmanager like Raindrop earlier.

    I use it to save articles,posts from reddit,memes, youtube video links and much more. Basically, anything I want to refer to later, I just save it to Raindrop.

  2. Seal

    Seal is a video/audio downloader based on yt-dlp. The app is really good. I love how quick and easy to use it is. The UI is pretty awesome too. You can download it from F-droid or directly from GitHub

  3. Paisa

    Paisa is a an expense and budget tracker. The app does a pretty good job but I think it is pretty overkill for an expense and budget tracker. I might switch from it to a more simple budget tracker. But until then, I am just going to keep using this app.

  4. Obsidian

    I use Obsidian for journalling. I love the offline approach of Obsidian and data doesn't leave my device.

  5. Notion

    I play the keyboard (Beginner) at my church and I needed something to keep track of the songs sung by our choir, so I found it really easy to set up a database in notion and also published it as a page on the web.

Push an existing local repository to GitHub

How to push an existing local repository to GitHub

Make sure the default branch name is 'main'.(main is the default branch name in my case.)

  1. Create a new repo on GitHub. The repository should be empty.

  2. Copy the URL of the repo on GitHub

  3. Add the copied URL as remote URL.

    git remote add origin REMOTE-URL

  4. Push the repo

    git push origin main

Useful Git Commands

git log --oneline

  • git log --oneline can be used to see the list of commits in a repo

git reset --hard HEAD~1

  • Used to reset the most recent commit.
  • All staged and unstaged changes are destroyed.

git reset --soft HEAD~1

  • All changes from the removed commit remain staged
  • But commit goes back by 1

git stash

  • If you are working on a branch and you need to switch to another branch to work on something else, then git will not allow you to do so if you have uncommittedd changes.
  • In such a situation, git stash can be used to temporarily save uncommitted changes. It reverts your directory to the last committed state.

Use git stash when you want to record the current state of the working directory and the index, but want to go back to a clean working directory. The command saves your local modifications away and reverts the working directory to match the HEAD commit.

  • Use git stash pop when you are ready to add the changes back to your code

git commit -am

  • Instead of using git add . then git commit -m "commit message", you can use

    git commit -am "message"

View git remote URL

  • git remote -v to view the remote URLs of a repository.

Some Tips

  1. If you are a CS student, learn how to use git.

  2. Don't waste your money on pointless internships and certifications.

  3. Doing an internship where you have to pay money out of your pocket is a scam and best not to do it. (Speaking from experience.)

  4. First year of Engineering is difficult (But it depends on person to person), study well during this time. Work hard.

  5. If you find a subject difficult to understand and you think you are going to fail then ask for help from your friends or go to tuition (there is nothing embarrassing about it). Don't be lazy and fail the subject on purpose.

  6. YouTube,ChatGPT & the world wide web are your friends, use the resources available to learn stuff.

  7. If you do fail a paper, it is not the end of the world. Work hard and clear the paper in the next semester.

  8. Don't get into any stupid fights and don't do anything that might get you suspended from college.

  9. Does CGPA matter? Well, the answer can be Yes/No. But if you are looking to get placed, then having a CGPA above 7.5 is good. If you can get your CGPA above 8,even better.

  10. Perform well and get good marks on internals or just enough marks to pass internals.

  11. Regardless of your branch(CS,Mech,Civil...), It's always to good know a programming language such as Python, C, etc.

  12. If you are willing to put in the effort, you can pass sem exams even if you start studying a few days before the exam or during study leave.

  13. If you can, try to do an actual internship (like the one where you get paid) in the final year. (I couldn't do it but this is a great thing to do. You will learn a lot.)

  14. During placement drives, prepare for aptitude test and practice questions.

  15. Having a strong grip over the basics. If you know Python, you should know it's basics too. In technical interviews, you will be asked mostly about the basics.

  16. Have a boatload of fun with your friends.

  17. You should try using Linux instead of Windows.

Useful Stuff for KTU

A collection of playlists, youtube videos and channels and websites that I use for studying.

Subreddit

r/KTUKerala - unofficial subreddit for KTU Students. It's a decent place for asking questions and having discussions.

Previous Year Questions

S1 & S2

For first year, I mostly referred to the prescribed textbooks.

Engineering Mechanics

Engineering Physics

S3

DSA (Data Structures & Algorithms)

LSD (Logic System Design)

OOP (Object Oriented Programming) in Java

  • Head First Java: A Brain-Friendly Guide This is actually a really good book that I found helpful. All the important concepts are explained in simple language with plenty of examples. The book was pretty fun to read.

S5

FLAT (Finite Language and Automata)

S6

Computer Graphics

Linux

My Linux Journey

1. Debian

Debian is the first distro that I installed on my computer.

I got tired of Windows 10 and decided to switch to Debian 12 (bookworm) in the month of July of 2023. No dual-boot. Just only Debian.

I used a Dell Inspiron laptop at the time and the hardware worked really.

Not only that Debian is a rock solid distro and I didn't face any big issues while using, everything worked well.

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2. Fedora

I think I used Debian Bookworm for a year and when I got my new laptop - A Lenovo Thinkpad E16, I decided to switch to a more up to date distro. So I chose Fedora.

Fedora is a solid distro and my thinkpad worked really well with it.

3. OpenSuse Tumbleweed (Current Distro)

Tumbleweed is what I am using right now.

After trying out Fedora for a while, I decided why not switch to a rolling release distribution. I could have gone with Arch but I thought why not try something different? Opensuse Tumbleweed was something that I had in my mind for a while and I really wanted to try it. So I went ahead and installed it.

Tumbleweed has been pretty good so far and I haven't faced any major issues so far. It's works pretty well considering it is a rolling release.

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Desktop Environment

Gnome

Gnome is the desktop environment of my choice. I love how clean, minimal and polished it is. Gnome just looks so good and I love the MacOS style it has.

Yes, I know how a lot of people just hate Gnome and I totally understand you guys. But I love gnome and it's enough for me.

Yes, I have tried KDE Plasma but it's just full of way too many options and customizations that I really don't need. Whenever I installed Plasma, I always felt like going back and installing Gnome.

Yeah so Gnome is my favorite distro.

Using tar.gz

I decided to try out the jetbrains applications. This is how I use the tarball.

Once the file is downloaded, you have to extract the file. The application can be launched by executing the ./bin/ WebStorm.sh script.

But it is much easier to launch the application by adding the directory to the PATH

  1. Extract the file

  2. Add directory to PATH

    nano ~/.bashrc

    export PATH=$PATH:/path/to/directory/

  3. Reload the shell environment

    source ~/.bashrc

apt package manager

Search for a package

To search for a package from the command line, use: apt-cache search keyword

Show package details

To show package details, use apt show package-name.

Basics of Vim

I just put this here so I can for future reference. Of course, there are many cheatsheets and guides on how to use vim. This is just my personal cheatsheets. I am not planning on adding every command, only just some useful ones.

If you find any mistakes here, please let me know.

Additional Reference

Start

Vim has basically four modes:

  1. Normal Mode (Command Mode) - the default mode.
  2. Command Line Mode - Play around with commands
  3. Insert Mode - for editing the contents of the file
  4. Visual Mode - for selecting the text.

How to enter each modes?

  • Press Esc to enter normal mode.
  • Press i to enter insert mode.
  • Press v for visual mode.
  • Press : to enter command line mode.

Saving and Quitting

Enter command mode

  • Use :w to save the file
  • Use wq to save and quit
  • Use q! to exit the file without saving changes made to the file
  • Use q if no changes were made.

Cursor Movements

  • h - to move left
  • l - to move right
  • j - move cursor down
  • k- move cursor up
  • G - to move to the last line
  • $ - to move to the end of a line

More commands for insert mode

  • o - insert new line after the current line
  • O - insert line before the current line
  • a - insert after cursor
  • i - insert before cursor
  • A - insert at end of line
  • I - insert at beginning of line

Undo Redo

  • u - Undo
  • Ctrl + R - for redo

Set line numbers or relative line numbers

  • set number - to display line numbers
  • set relativenumber - to display relative line number

Debian Mirrors

The sources file is located at /etc/apt/sources.list. More info on the sources.list file can be found on the Debian Wiki.

Mirrors that I use:

More mirrors can be found on the Free Software Mirrors in India page.

Check if port is in use

To check which ports are in use and find which application is listening to which port. Use the following command:

sudo ss -tulpn | grep LISTEN

The command options are:

  • -t:TCP Ports
  • -u: UDP Ports
  • -l: listening sockets
  • -p: process using the port

Source

Thinkpad

I use a Lenovo ThinkPad E16 Gen 2 (AMD) with Fedora as my Operating System.

Operating System

  • Fedora 41 Workstation
  • GNOME Desktop

Specifications

  • Processor AMD Ryzen™ 5 7535U Processor (2.90 GHz up to 4.55 GHz)
  • Graphic Card Integrated AMD Radeon™ 660M
  • Memory 16 GB DDR5-4800MHz (SODIMM)
  • Storage 512 GB SSD M.2 2242 PCIe Gen4 TLC Opal
  • Display 40.64cms (16) WUXGA (1920 x 1200)
  • IPS, Anti-Glare, Non-Touch, 45%NTSC, 300 nits, 60Hz
  • Camera 720P HD RGB with Microphone and Privacy Shutter
  • Battery 3 Cell Li-Polymer 47Wh
  • WIFI Realtek 8852BE WIFI 6 2x2ax + BT5.x & Bluetooth® 5.1 or above

More information can be found in the PSREF

Charging Thresholds

To extend the lifespan of your battery, you can define charging thresholds.

A ThinkPad battery can be set for maximum runtime (hours), or for maximum lifespan (years).

More info

Setting the Charging Thresholds

Source: Reddit

  • You can set the charging start threshold in (At what value or below should charging start):

    /sys/class/power_supply/BAT0/charge_start_threshold

  • You can set the charging stop threshold in (At what value charging should stop):

    /sys/class/power_supply/BAT0/charge_stop_threshold

  • I have set the start threshold at 75 and stop threshold at 80 on my laptop

Optimizing for runtime (hours)

Source: Lenovo

The normal default Lenovo Power Manager Battery Maintenance setting keeps the battery fully charged. The setting starts charging when the battery drops below 96%, and stops at 100%. The battery runtime depends on the Power Plan settings.

Optimizing for lifespan (years)

Source: Lenovo

For maximum lifespan when rarely using the battery, set Custom charge thresholds to start charging at 40% capacity and stop at 50%, and keep the ThinkPad cool. The thresholds can be adjusted in the Battery Maintenance settings of Lenovo Power Manager.

If the battery is used somewhat frequently, set the start threshold at around 85% and stop at 90%. This will still give a good lifespan benefit over keeping the battery charged to 100%.

Swap Fn and Ctrl Key

On thinkpads for some reason, the function and control keys are in a different position. I have no clue why Lenovo does this.

Anyway, if you prefer, you can swap the keys by using the BIOS. Please refer this article by Lenovo to swap the function and control keys.

Linux Installation

You can install any distribution on your laptop. In my opinion, it is better to go with Fedora or Ubuntu to make sure the hardware works as intended.

Update System and BIOS

  • Before getting rid of Windows, update the BIOS using Lenovo Vantage software. For more information, visit Lenovo's website

Disable Bitlocker Encryption

Before installing Linux on your ThinkPad, you must check if Bitlocker encryption is enabled on your disk.

If BitLocker encryption is enabled, please disable it before following the below steps.

You must disable bitlocker encryption to install Linux and backup your keys

Secure Boot

What is Secure Boot?

UEFI Secure boot is a verification mechanism for ensuring that code launched by firmware is trusted. More info can be found in the Ubuntu Wiki

Enable Secure Boot

The Bitlocker recovery screen will appear on changing the BIOS settings. Make sure you have bitlocker encrpytion disabled and have a backup key of your recovery key. The screen appeared for me because I hadn't disabled Bitlocker.

Source of Instructions: Lenovo

  1. Reboot your PC
  2. Boot into the BIOS setup menu by pressing the F1 key when the Lenovo logo is displayed
  3. In the BIOS menu select the “Security” option and the “Secure Boot” sub-menu. Toggle the “Allow Microsoft 3rd party UEFI CA” to be “On” as shown below. BIOS of Lenovo
  4. Press F10 to save and reboot

Linux Install

  1. Flash the ISO on to a USB using Rufus, Balena Etcher or the software of your choice (Since I use Fedora, I used Fedora Media Writer)
  2. Take your freshly written USB key and insert it in the powered down installation platform.
  3. Power on the device and press F12 during early boot to enter the Boot Menu.
  4. Navigate down to the USB HDD device and press Enter.
  5. Select the appropriate option from the GRUB Menu (In my case it was Test this media & start Fedora-Workstation-Live.)

Updating the BIOS

Please also refer to the references used to write these instructions

You should always be careful when updating the BIOS. I will not be responsible for any damage caused to your system. Always take the necessary precautions and follow the instructions carefully.
If you are on Windows, you can easily update the BIOS with Lenovo Vantage.

But on Linux distributions, Lenovo Vantage is not supported and since Thinkpad 16 G2 (AMD) is not Linux certified, you cannot get udate the BIOS using fwupd.

You can manually update the BIOS by downloading the image and flashing it on to a USB Drive.

  1. Download the BIOS image from Lenovo Support. Make sure you choose the correct model. You should download the CD ISO image.

  2. Download geteltorito

  3. Change directory to geteltorito

  4. Set permissions by using the below command

    chmod +x ./geteltorito.pl

  5. Extract the bootable image from the ISO:

    ./geteltorito.pl -o bios.img iso_file.iso

The below command will delete everything in your USB Drive. Make sure you don't have any important files in it
When copying the image in your USB stick, make sure you have chosen the correct device
6. Copy the image into your USB stick by dd utility 
sudo dd if=bios.img of=/dev/sdb

You now have a bootable USB drive.

Secure boot must be disabled it for the computer to boot the USB drive

ffmpeg

  1. Convert all the files in a particular directory to another format

    • For Linux and macOS this can be done in one line, using parameter expansion to change the filename extension of the output file 
      for i in *.avi; do ffmpeg -i "$i" "${i%.*}.mp4"; done

    Source

scrcpy

scrcpy (screen copy) is a tool used for mirroring and controlling your Android device via ADB. I found this tool particularly useful when I cracked the display on my phone and touch did not work properly.

To use scrcpy, you will need to enable USB Debugging on your device

You can download scrcpy from GitHub. To install it on Linux, see the following page.

  • To control the device using your keyboard and mouse (without Android Debugging). Use the following command.
scrcpy --otg
  • To mirror the device and control the device, simply run the following command
scrcpy
  • Use with the screen off
scrcpy --turn-screen-off --no-cleanup

source

Screenshot

alt text

ytdlp

  1. Download a video from YouTube as mp3

    yt-dlp --audio-format mp3 --add-metadata https://www.youtube.com/watch?v=r5PtlHs9igM

  2. Download video without audio

    yt-dlp youtube_link -F

pdftk

Merge Multiple PDFs into a single PDF

pdftk file1.pdf file2.pdf cat output output.pdf

Syncthing

I use syncthing to sync files between devices.

Note: On mobile, make sure syncthing is actually running. I was puzzled to find why syncthing wasn't running on my phone after I had installed it. Since battery saving mode was ON, the service hadn't actually started running. Just keep this in mind, if syncthing doesn't actually connect or sync properly.

Syncthing supports encryption for folders shared with devices. The data in the folder will be encrypted using a password and also can be decrypted using the same password.

For more info, refer to the syncthing docs

For decrypting the folder, use the command:

syncthing decrypt --to <plaintext-destination> --password <your-password> <encrypted-folder-path>

systemd

Start a service

systemctl start <service-name>

Stop a service

systemctl stop <service-name>

Restart a service

systemctl restart <service-name>

Reload a service

systemctl reload <service-name>

Enable service at boot

systemctl enable <service-name>

Disable service at boot

systemctl disable <service-name>

VS Code

VS Code is the text Editor of my choice.

Extensions I use

  1. Live Server

  2. SQLite Viewer

  3. Postman

CSS

Improving CSS Reset

How you can make your site a little bit more better by using the css below. Source

h1,
h2,
h3,
h4,
h5,
h6 {
  text-wrap: balance;
}

p,
li,
figcaption {
  text-wrap: pretty;
  max-width:65ch;
}

Dark Theme

How to add dark theme to a website using only css.

@media (prefers-color-scheme: dark) {
  img {
    opacity: .75;
    transition: opacity .5s ease-in-out;
  }
  img:hover {
    opacity: 1;
  }
}

Source

Virtual Environment (venv)

Linux

I sometimes forget how to create a virtual environment when workinng on something.

To create a venv on Linux:

python3 -m venv venv

To activate the venv:

source venv/bin/activate

To deactivate the venv:

deactivate

Create a venv for a particular python version

Just specify the version number that's all.

python3.10 -m venv venv

Setting up a Printer with EG8145V5

How to set up a printer on Huawei EG8145V5 rotuter?

This guide focuses on Linux users but even if you are a windows user - you can follow this video

  1. First connect the printer to the USB port and turn on the printer.
  2. Access the router gateway (192.168.18.1) in your browser. You may have a different gateway address....see the back of your router.
  3. Enable printer and storage sharing. Note the name of the printer as you will need it. You need to press the icon of of USB port to access the below settings. See image below.

Screenshot of router gateway...choose the USB option on the router home page to access the settings of devices connected to the ISB port

  1. Open CUPS by going to http://localhost:631 in your browser.
  2. Go to the administration section and add the printer
  3. Choose Internet Printing Protocol (ipp)

alt text

  1. Enter the url as http://192.168.18.1:631/printers/name_of_printer. Replace name_of_printer with the name you noted down earlier from the router's gateway.
  2. Choose the manufacturer of your printer. On the next page choose the correct model and try printing a test page.
  3. Your printer should be working.